Overt production of inflammatory cytokines such as IL-23 has been implicated in a number of diseases including multiple sclerosis, asthma, rheumatoid arthritis, inflammatory bowel diseases, Crohn's disease and psoriasis. Over 10 million people in the United States are affected by these IL-23 mediated diseases. Systemic levels of IL-23 are found to be associated with rheumatoid arthritis. (Melis, et al., Ann. Rheum. Dis. 69: 618-623, 2010). IL-23 gene knock-out mice are found to be resistant to development of many inflammatory diseases, indicating a crucial role of IL-23 in the pathogenesis of the disorders. (Langowski, et al., Nature, 442:7101, 2006). Single nucleotide polymorphisms in the IL-23 receptor genes have been associated with psoriasis. (Capon et al., Hum. Genet. 122:201-6, 2007). A single nucleotide polymorphism in the IL-23 receptor gene has been found to be associated with Crohn's disease and inflammatory bowel diseases. (Duerr, et al., Science, 314:1461-1463, 2006).
At a structural level, cytokine IL-23 is a heterodimeric cytokine that consists of two subunits (i.e., p19 and p40). The mature p19 subunit contains 170 amino acid residues in a 4 α-helix bundle, and the mature p40 subunit contains 306 amino acid residues consisting of three sequentially arranged β-strands. (Oppmann, et al., Immunity 13 (5): 715-725, 2000). Binding of IL-23 to its corresponding receptor (i.e., IL-23R) mediates cell signaling. For example, binding of IL-23 to IL-23R stimulates the production of IL-17, which is a key inflammatory mediator. IL-23R is a heterodimeric receptor consisting of an IL-23Rα subunit and an IL-12Rβ1 subunit. (Parham, et al., J. Immunol., 168:5699-5708, 2002). Interestingly, the IL-12Rβ1 subunit is shared with the IL-12 receptor.
Several researchers have reported using anti-IL-23 antibodies or IL-23 agonists in an attempt to disrupt IL-23 signaling. These studies shed light on the potential clinical applications in treating IL-23 related diseases. For example, U.S. Pat. No. 7,790,862 discloses the use of anti-p19 antibodies. Anti-p19 polyclonal antibodies reduced IL-17A and IL-17F production in a murine splenocyte assay. These authors purported that such anti-p19 antibodies may have utility in treating inflammatory diseases and cancer. U.S. Pat. No. 7,282,204 discloses the use of anti-p19 and anti-p40 antibodies. The authors claimed that anti-p19 antibodies reduced cancer volume in skin tumors, while anti-p40 antibodies provoked weight gain as to reduce cachexia. U.S. Patent Publication No. 2010/0166767 discloses the use of humanized anti-IL-23R antibodies. The authors determined the equilibrium dissociation constant for the created humanized anti-human IL-23R antibodies (i.e., Kd of Hum20D7 is 131 pM). U.S. Pat. No. 7,575,741 discloses the generation of an IL-23 fusion protein comprising the p19 subunit linked to the p40 subunit. The fusion protein is found to have property of enhancing wound healing in various mouse models.
The use of anti-p40 antibodies in inhibiting IL-23 activity, however, has many drawbacks. In particular, because the p40 subunit is shared by the IL-23 and IL-12 cytokines, anti-p40 antibodies may have the unintended consequence of inhibiting IL-12, demonstrating their non-specific effects (See, e.g., Oppmann, et al., Immunity 13:715-725, 2000; Cua, et al., Nature 421:744-748, 2003). Similarly, knocking out the p40 subunit has the dual affect of knocking out both IL-23 and IL-12.
Antibody-based approaches to inhibit IL-23R mediated signaling have additional shortcomings. First, it is recognized that antibody therapy often elicits an adverse immune response to the foreign administered antibodies during treatment. Second, repeated administration of antibodies (e.g., rodent-derived antibodies) potentially leads to fatal anaphylactic responses and suffer from loss in therapeutic efficacy and potency. Third, use of chimeric antibodies (i.e., antibodies in which mouse variable regions are fused with human constant regions) still possesses unwanted immunogenicity, albeit they may attenuate some anaphylactic responses. Fourth, while use of humanized antibodies (i.e., antibodies generated by grafting rodent CDR loops to human frameworks) may remedy the immunogenicity issues, preparation of humanized antibodies often leads to less effective antibodies (i.e., reduced antibody binding activity).
Although the amino acid sequence of IL-23R is known, there has been no report relating to the crystallization study of the molecular structure of IL-23R. Relying on the linear amino acid sequence with the aid of computer modeling, Chemtob et al. generated peptides that correspond to the hinge regions within the D1, D2 and D3 of the IL-23R. These authors disclosed in the U.S. Patent Publication 2010/0190710 ('710 application) that their IL-23R based polypeptides (e.g., LPDEVTCV (SEQ ID NO: 171), TEEEQQYL (SEQ ID NO: 172), KKYLVWVQ (SEQ ID NO: 173), and MEESKQLQL (SEQ ID NO: 174)) may represent potential antagonists of IL-23R. In particular, the '710 application discloses certain polypeptides can inhibit IL-23R mediated cell signaling (i.e., STAT3 phosphorylation). They reported using polypeptides that mimic IL-23R and function as IL-23R antagonists.
There is a continuing need for the discovery of novel polypeptides that inhibit IL-23 mediated cell signaling and diseases. The present inventors report herein, using a novel phage display approach, the identification of novel polypeptides that can bind to IL-23R. There is also disclosed the structure of these polypeptides, its compositions and methods of treatment using same in inhibiting binding of IL-23 to its receptor thereof and the subsequent cell signaling events. The novel polypeptides have utility in clinical application in the treatment of IL-23 mediated immuno-diseases.